A drill string is used in oil and gas exploration and production to reach subterranean destinations or formations. A drill string is assembled during drilling operations by joining tubular sections that include drill pipe, transition pipe, and a bottom hole assembly (“BHA”). An individual section of drill pipe may be referred to in the art as a joint. A pre-assembled group of two or more joints may be referred to in the art as a stand. As the well is drilled, joints or stands are added to the drill string from the surface until the desired depth is reached. The BHA typically includes a drill bit, drill collars, and drilling stabilizers. The drill collars may include downhole tools. The drill pipe and drill collars may be joined together using threaded connections. Subs may be used to connect sections with dissimilar threads.
The drill collars may be approximately 6-10 feet (1.8 m-3 m) in length and may include tools such as a downhole motor, a rotary steerable or directional drilling system, measurement while drilling (“MWD”) equipment, logging while drilling (“LWD”) equipment, and telemetry systems. A joint is typically on the order of 30 feet (9.1 m) long and has a small diameter and a relatively long length such as a depth to bore diameter ratio greater than 10:1. For example, each joint may include a diameter ranging from 1.5 to 5 inches and a length of 30 feet.
The components or modules within a drill string may include complex internal bore features that form conduits for routing wires or directing fluids through the drill string. The bore features may be formed parallel to, at an angle to, and/or perpendicular to a center line passing axially through the drill string.
Existing manufacturing techniques employ sophisticated equipment such as “gun drilling” to bore long and narrow passages axially through the sections. Existing manufacturing techniques must meet particular angle tolerances, profile tolerances, or positional tolerances to precisely form conduits or passages through the sections. As a result, partially completed portions of sections may need to be discarded and re-manufactured due to design tolerance faults.